The present invention relates to fluid coupling devices, and more particularly, to fluid coupling devices of the type normally referred to as "torque responsive".
Although fluid coupling devices of the type to which the present invention relates have many applications, the present invention is especially suited for use with fluid coupling devices for driving the radiator cooling fan of a vehicle engine, and will be described in connection therewith.
Fluid coupling devices of the type to which the present invention relates normally comprise an output coupling member which cooperates with a cover to define a fluid chamber therein. Disposed within the fluid chamber is an input coupling member which cooperates with the adjacent surface of the output coupling member to define a shear space. The shear space is filled with a viscous fluid (typically, a silicone fluid) and torque is transmitted from the input member to the output member by means of viscous fluid shear. Thus, fluid couplings of this type are also referred to as viscous couplings, and when used for driving radiator cooling fans are referred to as viscous fan drives.